1. Field of Invention
The invention relates to a liquid droplet patterning apparatus, and more particularly, technologies for varying an ejection pitch when a recording operation is performed by ejecting liquid droplets, enabling to eject liquid droplets of a plurality of kinds, and finely, precisely adjusting a nozzle head in a sub-scanning direction.
2. Description of Related Art
In recent years, various types of ink-jet printers have been put to practical use. Color ink-jet printers that can perform a recording operation in colors with high resolution at the same level as that of a picture are becoming increasingly common. In the ink-jet printers, a plurality of nozzle heads are attached to a carriage, and, for example, 128 nozzles are provided in each nozzle head so as to align in a row or in a plurality of rows. By ejecting ink droplets from the nozzles, an image is recorded with a dot pattern. Japanese Laid-Open patent publication No. 11-334049 discloses technology for changing a nozzle pitch by rotating the nozzle heads by moving a movable link with respect to a fixed link in order to perform the recording operation in various nozzle pitches.
Commonly, a liquid crystal display is adopted to use with personal computers, word processors, copying machines, facsimile machines, cellar phones, and various portable terminals. Lately, color liquid crystal displays, which can display in color via a color filter, are also used widely. The color filter is provided by which pixels of the primary colors of lights (red R, green G and blue B) are regularly formed with a dot pattern on a transparent film. The color filter can be produced using a liquid droplet patterning apparatus similar to the ink-jet printer.
Japanese Patent No. 3121226 discloses a liquid droplet patterning apparatus for providing the color filter. In the liquid droplet patterning apparatus, a dot pattern is formed on a glass substrate using red, green and blue liquids by ejecting liquid droplets from a plurality of nozzles provided in each of red, blue, and green nozzle heads. Japanese Patent No. 3121226 suggests a technique for performing the recording operation with a dot pitch (ejection pitch), which is narrower than a nozzle pitch, by adjusting the dot pitch by rotating the nozzle heads with respect to a sub-scanning direction. Japanese Patent No. 3121226 also suggests a technique for aligning a recording starting position of the glass substrate by shifting timings of ejection from nozzles no. 1 to no. N when the nozzle heads are rotated, and a technique for controlling ejection timings so as to correct a positional deviation of each nozzle from a center line of the plurality of the nozzles in each nozzle head.
Japanese Laid-Open Patent Publication 9-300664 discloses a liquid droplet patterning apparatus that provides a color filter used for the color liquid crystal display. In this apparatus, red, green and blue nozzle heads, having a plate-shape and extending in a direction perpendicular to a glass substrate, are disposed in parallel with a sub-scanning direction.
Both ends of each of the nozzle heads are supported by a holder. One end of each holder is rotatably connected to a head mount (frame) by a rotational shaft, and the other end is rotatably connected to a sliding member by a rotational shaft. Each of the nozzle heads is urged toward the one end of each nozzle head by a coil spring, and can be adjusted in its position with respect to the one end of the holders using a fine adjustment screw. In addition, a fine adjustment screw for finely moving the sliding member with respect to the head mount is provided. By adjusting a position of the sliding member in a main scanning direction using the fine adjustment screw, a rotation angle of the three nozzle heads with respect to the sub-scanning direction is changed to adjust a dot pitch in the sub-scanning direction appropriately.
An organic electroluminescence (EL) display has been put into practical use as a next-generation display substitute for the above-described liquid display. An EL substrate used for an organic EL display is, for example, a glass substrate, on which an anode layer, a hole transport layer, an emitter layer, and a cathode layer are formed. Various luminescent organic compounds are applied as the emitter layer according to desired luminescent colors. In the emitter layer of the EL substrate for the color EL display, red (R), green (G) and blue (B) luminescent elements are regularly formed into a dot pattern. The organic EL display has a slim body, is lightweight and low in cost as well as having a simple structure. In addition, the organic EL display offers excellent visibility through a wide viewing angle and needs little power.
The EL substrate for the organic color EL display is produced as described below. Liquid droplets for forming a hole transport layer are ejected onto a glass substrate from the nozzle heads of the liquid droplet patterning apparatus, and then the liquid droplets on the glass substrate are fixed by heat in a vacuum or an inert atmosphere (gas). After that, three kinds of liquids corresponding to R, G, B, for forming an EL emitter layer, are ejected from the three nozzle heads onto the glass substrate to form a dot pattern. Next, heat is applied to the dot pattern in the vacuum, and then an electrode layer (cathode layer) is formed thereon by evaporating aluminum.
Japanese Laid-Open Patent Publication No. 11-334049 discloses the ink-jet printer that rotates the nozzle heads by moving the movable link with respect to the fixed link. Therefore, in order to maintain the nozzle heads at the rotated position, at least the fixed link, the movable link and the nozzle heads need to be attached to the head mount. In this structure, however, because the movable link moves along an arc with respect to the fixed link, the structure of the ink-jet printer becomes complicated. Accordingly, it should become difficult to design a nozzle head unit including nozzle heads.
Japanese Patent No. 3121226 does not disclose a mechanism for supporting the nozzle heads so that the nozzle heads can rotate with respect to the sub-scanning direction, nor an actuator for rotating the nozzle heads. A plurality of the nozzle heads are not detachably attached as a nozzle head unit. Japanese Patent No. 3121226 does not mention a center of rotation when the nozzle heads are rotated.
Japanese Laid-Open Patent Publication No.9-300664 discloses the liquid droplet patterning apparatus that requires three nozzle heads deposed in a standing posture, so that the shape of the nozzle heads is limited. When the nozzle heads are designed such that the nozzle heads can be attached to and detached from the holders at both ends from above, it is difficult to precisely set a position of the nozzle heads in a vertical direction. On the other hand, when the nozzle heads are designed such that the nozzle heads cannot be attached to and detached from the holders at both ends from above, it becomes difficult to remove the nozzle heads easily when the nozzle heads are repaired or replaced. Thus, the maintainability cannot be ensured.
Further, in the liquid droplet patterning apparatus, the sliding member needs to be moved in the main scanning direction by manually operating the fine adjustment screw, every time a dot pitch (ejection resolution) in the sub-scanning direction is changed. Therefore, it is impossible to set a maximum rotation angle for inclining the nozzle heads to a very large angle. Thus, a range of the dot pitch that can be accomplished by the rotation of the nozzle heads becomes narrow.
The invention provides a liquid droplet patterning apparatus wherein a nozzle head is easily attached and detached, maintainability of the nozzle head is improved, a variable range of an ejection pitch is extended by extending a range of a rotation angle that the nozzle head can rotate, and an adjustment of an ejecting position is easily performed by nozzle by moving the nozzle head in a sub-scanning direction regardless of the rotation angle of the nozzle head.
According to one aspect of the invention, a liquid droplet patterning apparatus includes a plurality of nozzles that eject liquid droplets onto a recording medium, a plurality of nozzle heads aligned in a main scanning direction, at predetermined intervals, a plurality of rotation devices, a plurality of sliding mechanisms and a plurality of position adjusting devices. The plurality of the nozzle heads have the plurality of the nozzles aligned in a sub-scanning direction orthogonal to the main scanning direction. The plurality of the support members rotatably support the respective nozzle heads. The plurality of the rotation devices rotate the respective nozzle heads about an axis extending in a direction parallel to the liquid droplet ejecting direction and orthogonal to the nozzle alignment direction, with respect the support members. The plurality of the sliding mechanisms slidably support the plurality of the support members in the sub-scanning direction. The plurality of the position adjusting devices finely adjust the respective support members, which support the nozzle heads, via the sliding mechanisms, in the sub-scanning direction.